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MODULE 15 - Cardiorespiratory and Haematopoietic Disease > PATHOLOGY - Canine Acquired Cardiac Disease > Flashcards

PATHOLOGY - Canine Acquired Cardiac Disease Flashcards

1
Q

What is myxomatous mitral valve disease?

A

Myxomatous mitral valve disease is a degenerative valvluar disease characterised by changes in the cellular and intracellular constituents of the valve, resulting in valve leaflet and chordae tendinae thickening

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2
Q

Which signalment is more prone to myxomatous mitral valve disease?

A

Medium sized, older male dogs

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3
Q

Which dog breed is predisposed to myxomatous mitral valve disease?

A

Cavalier King Charles Spaniels

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4
Q

Describe the pathophysiology of myxomatous mitral valve disease

A

The degeneration of the mitral valve results in valvular insufficiency, preventing complete apposition of the valve leaflets during systole resulting in blood regurgitation from the left ventricle back into the left atrium. This regurgitation eventually results in volume overload and left ventricular compensatory eccentric hypertrophy and left atrial enlargment. The hearts ability to pump blood effectively will progressively worsen along with the volume overload, this eccentric hypertrophy will also cause dilation of the valvular annular ring, resulting in a worsening regurgitation into the left atrium and a worsening volume overload which will eventually cause a backup of blood into the pulmonary veins, causing increased hydrostatic pressure resulting in pulmonary oedema and left-sided congestive heart failure. This can also progress to right-sided congestive heart failure as pulmonary hypertension will increase the afterload on the right side of the heart, resulting in pressure overload, concentric hypertrophy of the right ventricle and eventual right-sided congestive heart failure

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5
Q

What are the five clinical signs of myxomatous mitral valve disease?

A

Asymptomatic
Left sided apical systolic plateau murmur
Syncope
Exercise intolerance
Signs of left-sided congestive heart failure

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6
Q

What can be the three underlying causes of the cough seen with myoxmatous mitral valve disease?

A

Cardiogenic pulmonary oedema
Airway obstruction secondary to cardiomegaly
The signalement for myoxmatous mitral valve disease are also predisposed to respiratory disease

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7
Q

How can you determine the severity of myxomatous mitral valve disease on clinical exam?

A

The severity of the myxomatous mitral valve disease corresponds with with intensity of the heart murmur

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8
Q

What is indicated by a grade I or II heart murmur associated with myoxmatous mitral valve disease?

A

A grade I or II heart mumur indicates there is a mitral valve insufficiency but no cardiac remodelling (stage B1)

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9
Q

What is stage A of myxomatous mitral valve disease?

A

Dogs that are at risk of developing myxomatous mitral valve disease due to their signalement but have no structural or clinical signs

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10
Q

What is stage B1 of myxomatous mitral valve disease?

A

Dogs that have clear valvular insufficiency but there is no cardiac remodelling

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11
Q

What is stage B2 of myxomatous mitral valve disease?

A

Dogs with clear valvular insufficiency and cardiac remodelling

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12
Q

What is stage C of myxomatous mitral valve disease?

A

Dogs with clinical signs of congestive heart failure

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13
Q

What is stage D of myxomatous mitral valve disease?

A

Dogs with end-stage congestive heart failure and are refractory to treatment

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14
Q

What are the characteristic signs of myxomatous mitral valve disease on a radiograph?

A

Cardiomegaly (particulalry of the left atrium)
Dorsal displacement of the trachea due to left atrial enlargement
Displacement of the bronchi on VD by left atrial enlargement (cowboy sign)
Signs of left-sided congestive heart failure (such as perihilar alveolar lungs signs and increased size of the pulmonary veins)

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15
Q

Which three arrhythmias can sometimes be seen with myoxmatous mitral valve disease?

A

Atrial fibrillation
Supraventricular premature contractions
Ventricular premature contractions

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16
Q

What can be indicated by sinus arrhythmia in dogs with a murmur associated with myxomatous mitral valve disease?

A

Sinus arrhythmia indicates that the myxomatous mitral valve disease is not yet severe, and there is a low chance that there has been cardiac remodelling

However this can be misleading if the dog also has a disease causing high vagal tone

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17
Q

What are the characteristic signs of myxomatous mitral valve disease on echocardiography?

A

Thickened and nodular mitral valve
Left atrial enlargement
Left ventricular eccentric hypertrophy
Turbulent blood flow at the mitral valve (doppler)

Right parasternal long axis view of the left ventricle and atrium
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18
Q

Which two biomarkers can be indicative of myxomatous mitral valve disease?

A

NTproBNP
Cardiac troponin I

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19
Q

What can be indicated by increased plasma levels of NTproBNP?

A

NTproBNP plasma levels increase when cardiac size increases

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20
Q

Why is NTproBNP an unreliable biomarker of cardiac disease?

A

NTproBNP is non-specific to cardiac disease and has significant biological variability

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21
Q

What can be indicated by increased plasma levels of cardiac troponin 1?

A

Cardiac troponin 1 plasma levels increase when the is cardiac damage

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22
Q

In dogs at risk of myxomatous mitral valve disease, what should owners monitor for at home?

A

An increased resting respiratory rate as this can precede signs of left-sided congestive heart failure

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23
Q

How should you treat stage A myxomatous mitral valve disease?

A

No treatment

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24
Q

How should you treat stage B1 myxomatous mitral valve disease?

A

No treatment

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25
How should you treat stage B2 myxomatous mitral valve disease?
Treat with pimobendan
26
How should you treat stage C myxomatous mitral valve disease?
Treat with pimobendan and diuretics
27
What is the prognosis for dogs with myxomatous mitral valve disease exhibiting clinical signs of left-sided congestive heart failure?
Generally a prognosis of 9 months
28
What is dilated cardiomyopathy?
Dilated cardiomyopathy is an inherited generalised disease/dysfunction of the myocardium characterised by ventricular dilatation
29
Which signalement is more prone to dilated cardiomyopathy?
Large, middle age to old male dogs
30
Which dog breeds are predisposed to dilated cardiomyopathy?
Doberman Irish Wolfhound Bernese Mountain dogs
31
Describe the pathophysiology of dilated cardiomyopathy
Dilated cardiomyopathy is generalised dysfunction of the myocardium resulting in systolic dysfunction which causes a reduction in cardiac output which results in an increased end-diastolic volume, volume overload and compensatory ventricular eccentric hypertrophy. The hearts ability to pump blood effectively will progressively worsen along with the volume overload, resulting in a backup of blood into the pulmonary veins (on the left side of the heart) and systemic circulation (on the right side of the heart), increasing hydrostatic pressure resulting in pulmonary and systemic oedema and congestive heart failure
32
What are the seven clinical signs of dilated cardiomyopathy?
Asymptomatic Low grade or no mumur Arryhthmias Syncope Exercise intolerance Signs right and left sided congestive heart failure Weak pulses
33
Why is there often not a heart murmur associated with dilated cardiomyopathy?
There is not always a heart murmur as the primary issue in dilated cardiomyopathy is related to the myocardial structure and function rather than turbulent blood flow that typically results in a heart murmur
34
How does dilated cardiomyopathy cause arrhythmias?
Arrhythmias can occur due to structural damage to the heart due to dilated cardiomyopathy
35
Why is it recommended to begin screening for arrhythmias in breeds predisposed to dilated cardiomyopathy?
Arrhythmias can potentially cause sudden death so it is recommended to begin screening for arrhythmias from 3 years old in dog breeds predisposed to dilated cardiomyopathy, using a 24 holter ECG
36
(T/F) **Male** dogs with dilated cardiomyopathy develop structural changes before they develop arrhythmias
TRUE.
37
(T/F) **Female** dogs with dilated cardiomyopathy develop structural changes before they develop arrhythmias
FALSE. **Female** dogs with dilated cardiomyopathy develop arrhythmias before they develop structural changes
38
What is stage A of dilated cardiomyopathy?
Dogs that are at risk of developing dilated cardiomyopathy due to their signalement but have no structural or clinical signs
39
What is stage B1 of dilated cardiomyopathy?
Dogs that have arrhythmias but there is no cardiac remodelling
40
What is stage B2 of dilated cardiomyopathy?
Dogs that have cardiac remodelling ± arryhthmias
41
What is stage C of dilated cardiomyopathy?
Dogs with clinical signs of congestive heart failure
42
What is stage D of dilated cardiomyopathy?
Dogs with end-stage congestive heart failure that is refractory to treatment
43
What are the characteristic signs of dilated cardiomyopathy on echocardiography?
Eccentric ventricular hypertrophy Poor systolic function
44
Which two biomarkers can be indicative of dilated cardiomyopathy?
NTproBNP Cardiac troponin I
45
Which additional test can you do to help diagnose dilated cardiomyopathy?
24 hour arrhythmia monitoring using a holter ECG
46
How do you treat dilated cardiomyopathy?
Treat with pimobendan
47
What is the prognosis for dogs with dilated cardiomyopathy exhibiting clinical signs of congestive heart failure?
Prognosis of approximately a year, typically only 3-4 months in Dobermans
48
What is secondary dilated cardiomyopathy?
Secondary dilated cardiomyopathy is cardiomyopathy with an underlying pathological cause
49
Give an example of an underlying aetiology of secondary dilated cardiomyopathy
Nutritional difficiencies - such as taurine and L-cartinine deficiency
50
What is the most common acquired cardiac disease seen in Boxers?
Arrhythmogenic (right ventricular) cardiomyopathy (ARVC) | A form of primary dilated cardiomyopathy
51
Which other dog breed is predisposed to arrhythmogenic (right ventricular) cardiomyopathy (ARVC)?
English Bulldogs
52
Which diagnostic test is most useful for screening dogs with suspected arrhythmogenic (right ventricular) cardiomyopathy?
24 hour arrhythmia monitoring using a holter ECG
53
What is pericardial effusion?
Pericardial effusion is an abnormal accumulation of fluid within the pericardial cavity
54
What is the most common type of effusion in the pericardium?
Haemorrhagic effusion
55
Why is it important to do a PCV on the effusion collected from a pericardiocentesis?
You should do a PCV on the effusion as the PCV has to be above 10% to be classified as a haemorrhagic effusion
56
What is cardiac tamponade?
Cardiac tamponade is compression of the heart due to a pericardial effusion
57
Describe the pathophysiology of cardiac tamponade
Cardiac tamponade is compression of the heart due to pericardial effusion which restricts the filling of the cardiac chambers during diastole, resulting in decreased cardiac output. Cardiac tamponade has a more significant effect on the right side of the heart as the right side operates at lower pressures compared to the left side, which means the pericardial effusion will exert more pressure on the right-sided heart chambers, resulting in impaired filling, reduced output and eventually causing a backup of blood and right-sided congestive heart failure. Due to the reduced cardiac output from the right side of the heart into the pulmonary artery, there will be reduced venous return to the left side of the heart resulting in a decreased cardiac output
58
What is the difference between acute and chronic pericardial effusion?
Acute pericardial effusion is the life-threatening rapid accumulation of fluid in the pericardium and compression of the heart, whereas chronic pericardial effusion is the slow build up of fluid over time, allowing the pericardium to stretch out and accumulate more and more fluid until there is eventual compression of the heart
59
What are the seven clinical signs of acute pericardial effusion and cardiac tamponade?
Severe weakness/collapse Syncope Sudden death Dyspnoea Muffled heart sounds Tachycardia Pulsus paradoxus
60
What are the eight clinical signs of chronic pericardial effusion?
Exercise intolerance Increased thirst Vomiting Abdominal distension Muffled heart sounds Tachycardia Pulsus paradoxus Signs of right sided congestive heart failure
61
Why do you get muffled heart sounds with pericardial effusion?
The increased layer of fluid within the pericardium will cause the heart sounds to be muffled on auscultation
62
What can be detected on an ECG that is indicative of pericardial effusion?
Electrical alternans of the QRS complexes
63
How does pericardial effusion cause electrical alternans of the QRS complexes on ECG?
The fluid accumulation in the pericardial cavity creates a 'swinging' motion of the heart when it beats, which changes the position of the heart relative to the electrodes which can lead to a variation in the electrical signals detected by the ECG
64
How do you treat pericardial effusion and cardiac tamponade?
Pericardiocentesis
65
What are the two most common causes of pericardial effusion?
Idiopathic Neoplasia
66
Give an example of a congenital cause of pericardial effusion
Peritoneo-pericardial diaphragmatic hernia
67
What are the most common neoplastic causes of pericardial effusion?
Cardiac haemangiosarcoma *(most common and most aggressive)* Neuroendocrine tumours Pericardial mesothelioma
68
Which three breeds are predisposed to cardiac haemangiosarcomas?
German Shepherds Golden Retrievers Labrador Retrievers
69
Where are cardiac haemangiosarcomas usually found?
Right atrium Right auricle
70
Where do haemangosarcomas often metastasise to or from?
Spleen
71
What is a characteristic feature of haemangiosarcomas?
Haemangosarcomas have a high level of angiogenesis and these vessels often burst and cause haemorrhage - *i.e. if the dog also has a splenic haemangiosarcoma, there can be a haemoabdomen*
72
What is the most common neuroendocrine tumour that causes pericardial effusion?
Chemodectoma
73
(T/F) Chemodectomas are usually malignant
FALSE. Chemodectomas as usually benign however they can grow very large and compress the heart chambers
74
Why are brachycephalic breeds prone to chemodectomas?
Chemodectomas originate from chemoreceptors in the aortic root and can be triggered by hypoxia. Brachycephalics are hypoxic for the majority of their lifespan and thus are at increased risk of chemodectomas
75
(T/F) There is often no mass associated with pericardial mesotheliomas
TRUE. Often there is only pericardial effusion associated with pericardial mesotheliomas
76
What is constrictive pericardial disease?
Constrictive pericardial disease is the stiffening and reduced compliance of the pericardium *which restricts the filling of the cardiac chambers during diastole, resulting in decreased cardiac output and eventually congestive heart failure*
77
How do you treat constrictive pericardial disease?
Surgical removal of the pericardium
78
What is pulmonary hypertension?
Pulmonary hypertension is a pathological increase in the mean arterial pressure (MAP) of the pulmonary arteries
79
How does pulmonary hypertension cause right-sided heart failure?
Pulmonary hypertension increases the afterload on the right ventricle, causing pressure overload and compensatory concentric hypertrophy of the right ventricle which will eventually progress to right sided heart failure
80
What are five possible causes of pulmonary hypertension?
Primary pulmonary arterial hypertension Left sided heart disease Secondary to respiratory disease Pulmonary thromboembolisms Parasitic (heart and lungworms)
81
How do you diagnose dirofilaria immitis?
Positive antigen test for macrofilariae and a second confirmatory test such as detection of adult worms on echocardiography
82
Why is it so important to get a confirmatory test for dirofilaria immitis?
It is important to get a confirmatory test for dirofilaria immitis as melarsomine -one of the drugs used to treat this parasite - is arsenic based and can be very toxic, so you want to be very sure that it is indicated
83
How do you treat dirofilaria immitis?
Macrocyclic lactones to kill the microfilariae Melarsomine to kill the adult worms Surgical removal of the adult worms
84
What are the main clinical signs of an angiostrongylus vasorum infection?
Exercise intolerance Tachypnoea Coughing Signs of haemostatic disorder Cardiovascular dysfunction
85
How does a angiostrongylus vasorum infection increase coagulation time?
Angiostrongylus vasorum adults secrete products which interfere with coagulation and thus increase coagulation time
86
How do you diagnose an angiostrongylus vasorum infection?
Identify L1 larvae in the faeces using Baermann apparatus Antigen test Thoracic radiography
87
What are the changes on thoracic radiography that can be seen with angiostrongylus vasorum?
Abnormal lung patterns in the dorso-caudal lung fields | However this is not always seen
88
What can predispose dogs to endocarditis?
Subaortic stenosis Aortic valve regurgitation Corticosteroids
89
What are the four main consequences of infective endocarditis?
Persistent bacteraemia Valvular insufficiency Septic embolisation Antigen-antibody complex deposition
90
In which valves is endocarditis most commonly seen in dogs?
Mitral valve Aortic valve
91
Where on the mitral valve does endocarditis typically develop and why?
Endocarditis typically develops on the atrial side of the mitral valve as there is less pressure on that side which allows for better adherence of the bacterial vegetations
92
Where on the aortic valve does endocarditis typically develop and why?
Endocarditis typically develops on the ventricular side of the aortic valve as there is less pressure on that side which allows for better adherence of the bacterial vegetations
93
What are some of the potential clinical signs of endocarditis?
New or rapidly progressed heart murmur Pyrexia Hindlimb weakness
94
How does endocarditis cause a heart murmur?
Bacteria causing infective endocarditis produce proteinase enzymes which can cause structural damage to the heart valves, resulting in the inability of the valves to close properly resulting in the backflow, regurgitation and turbulence of blood, causing a heart murmur
95
What are the three major criteria required to diagnose endocarditis?
Echocardiogram positive for endocarditis Valvular insufficiency Positive culture result
96
Which diagnostic tests can you do to determine the source of infection in an animal with endocarditis?
Blood culture Urine culture Diagnostic imaging *(of the thorax and abdomen)*
97
How should endocarditis be treated?
Infectious endocarditis should be treated with high dose bactericidal antibiotics over a long duration (usually for six weeks or more)
98
What is myocarditis?
Myocarditis is inflammation of the myocardium
99
Which virus most commonly causes myocarditis in dogs?
Canine parvovirus 2

MODULE 15 - Cardiorespiratory and Haematopoietic Disease (21 decks)

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